This invention relates generally to window wipers and specifically to a window wiper motor system for an automotive vehicle.
Almost all automotive vehicles have a single or a pair of windshield wiper assemblies. These assemblies traditionally include rubber wiper blades mounted upon claw brackets. These claw brackets are pivotably attached to wiper arms mounted upon rotating shafts. The shafts are either directly driven by electric motors or driven by a single electric motor which actuates a series or parallel-coupled four bar linkage mechanism. It is further known to provide a wiper system, in combination with a wash device, to clean headlamps for automotive vehicles.
It is also common to employ a window wiper assembly for cleaning rear windows of automotive vehicles. Typically, these types of rear window wiper assemblies include a wiper blade mounted upon a bracket which is coupled to a wiper arm. The wiper arm is attached to a wiper shaft rotatably driven in a cyclical oscillating manner by a helical gear. A reversible, fractional horsepower, direct current electric motor serves to actuate the helical gear through an armature shaft mounted worm gear enmeshed therewith. This type of rear window wiper arrangement is usually mounted upon a pivoting liftgate of a minivan, station wagon, sport-utility vehicle or the like. One such example is disclosed in U.S. Pat. No. 5,519,258 entitled "System and Method for Controlling Vehicle Lift Gate Window Wiper" which issued to Stroven et al. on May 21, 1996.
Some conventional vehicles also provide a rear window release lock or latch, actuated by a solenoid, which can be unlocked to allow for upward pivotal movement of a rear window in relation to the otherwise stationary liftgate. In combination therewith, a separate liftgate lock is often mounted upon the liftgate door for fastening the liftgate to the body thereby preventing inadvertent pivotal opening. This liftgate lock is traditionally operated by manual key or handle rotation, or through a separate electric motor or solenoid.
Separate motors or solenoids are commonly required to actuate these various locks and the wiper. The traditional need for such a multiplicity of electromagnetic devices has increased the automotive vehicle weight and cost while further proving difficult to package within the often small spaces provided. This added weight is especially detrimental when the window wiper mechanism, rear window lock and liftgate lock, as well as their distinct respective electromagnetic devices, are all incorporated within the pivoting liftgate. Not only is the piece cost increased due to this multiplicity of electromagnetic devices, but the assembly cost, part number proliferation and handling costs, electric wiring costs, objectional motor noise, and failure modes are increased. Furthermore, U.S. Pat. No. 3,688,332 entitled "Mechanism for Opening and Closing a Cover for a Concealed Windshield Wiper System" which issued to Bellware on Sep. 5, 1972, discloses a windshield wiper driven by an electric motor and an interruptable driving connection controlled by a separate electromagnet. This device further employed levers and pivot pins to open and close a cover.
More recently, WO 96/33891 entitled "Multi-Functional Apparatus Employing an Intermittent Motion Mechanism," WO 96/33893 entitled "Multi-Functional Apparatus Employing an Electromagnetic Device," and WO 96/33892 entitled "Control System for an Automotive Vehicle Multi-Functional Apparatus," all of which were published on Oct. 31, 1996, disclose a significantly improved system wherein a single electromagnetic device can selectively operate intermittent motion mechanisms coupled to a window wiper, a door lock, a window release lock and the like.
Many conventional window wiper motor devices employ a conductive feedback disk mounted on and rotating with a main gear that drives a window wiper shaft. Multiple fingers or stationary contacts are fixed to a rigid printed circuit board or the gear housing for indicating the end of sweep positions of the main gear. Such a device is shown in U.S. Pat. No. 4,259,624 entitled "Arrangement For Wiping A Vehicle Window," which issued to Seibicke on Mar. 31, 1981. This limit switch-type arrangement merely acts as an on/off switch to determine whether the wiper and driving gear have reached the end of their mechanically predetermined and fixed travel; intermediate incremental wiper positions cannot be determined within the wiping sweep range. Therefore, if the wiping travel distance or range is different between vehicles, then the rotating conductive disk must be mechanically changed in length and replaced. This increases part numbers and manufacturing costs.